Electrodeposition of nickel



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ELECTRODEPOSITION OF NICKEL Henry Brown, Detroit, Mich., assignor to The Udylite Corporation, Detroit, Mich., a corporation of Delaware No Drawing. Application July 9, 1945, Serial No. 604,079

4 Claims. (01. 49)

My invention relates to'improvements in the electrodeposition of metals. It is particularly concerned with the utilization of certain addition agents, for the purposes hereinafter stated, in aqueous acidic electroplating baths.

I have discovered that certain substances, hereinafter described in detail, when added to electroplating baths, particularly aqueous acidic electroplating baths such as used for the electrodeposition of nickel, cobalt, iron, zinc, cadmium, copper, antimony, various alloyscontaining the aforementioned and other metals, and the like, are remarkably efiective in the prevention of the formation of pits in the electro-deposited coatings, said pits normally being caused by the adherence of gas bubbles during the electrodeposition of the coating. I have found, further, that this result is accomplished despite the fact that very low concentrations of the addition substances are employed and, still further, that these results are accomplished without causing any significantly appreciable interference'with the desired appearance, structure, and character of the plate. I have also discovered that the addition agents are highly effective independently of whether various'organic or inorganic so-called brightening agents are also present in'the electrolyte bath. Various addition agents have heretofore been suggested for reducing or eliminating pitting in electrodeposition operationsbut, at least in most cases, and apart from other deficiencies which they possess, they have proven to be wholly unsatisfactory where the electrodeposition bath contained brighteners. Thus, for example, in baths employed for the electrodeposition of bright nickel, where the brightening agent comprises an aryl sulphonic acid, for example, naphthalene 1,5 disulphonic acid, sodium salt, or sulphonamides or sulphonimides, forexample, saccharin, such as are disclosed in my Patent No. 2,191,813, issued February 27, 1940, various suggested anti-pitting agents haveproven entirely unsatisfactory. The use of the addition agents in bright plating baths represents but one aspect of my present invention although, to be sure, a highly important one;

,Theaddition agents which I have'found to be unusually satisfactory, in accordance with my present invention, can be used in sufficiently low concentrations so, as to-reduce substantially, or eliminate entirely, pitting of the deposits and, at the same time, they do not interfere to any significantly appreciable extent with the particular cathodic process involved such as reduction ofinorganiclor organic substancestaking place in the process of electrodepositing the coating.

This is highly important where the deposited metal is desired not only free from pits but also,

are employed.

The novel and highly useful addition agents which accomplish the functions set out hereinabove are, in general, sulpho-monocarboxylic acidv esters, particularly, sulpho-fatty acid esters, of water-soluble polyhydric alcohols partially etherified with aliphatic alcohols, particularly fatty alcohols, containing from 8 to 18 carbon. atoms. The sulphomonoc'arboxylic radical contains from 2to 6 carbon atoms, the sulphoacetates being particularly satisfactory. My 'copending application Serial No. 379,950, application February 21, 1941, now Patent 2,389,135, is directed to aliphatic sulpho-mono-carboxylic acid esters of aliphatic alcohols containing from 8 to 18 car-, bon atoms. My copending application Serial No. 379,951, application February 21, 1941, now Patent 2,389,179, is directed to sulphuric acid esters or sulphates of water-soluble polyhydric alcohols partially esterified with aliphatic carboxylic acids,- particularly fatty acids, containing from 8 to 18 carbon atoms. My copending application Serial No. 381,547, application March 3, 1941, now Patent 2,389,180, is directed to sulphocarboxylic acid esters, particularly, sulpho-fatty acid esters, of

water-soluble polyhydric alcohols partially esterified with aliphatic carboxylic acids, particularly fatty acids, containing from 8 to 18 carbon atoms.

Various of the addition agents utilized in ac-' cordance with the present invention may be represented by the formula where R is an alkyl radical containing from 8,

to 18 carbon atoms, M is a cation such as hydrogen, alkali metals or a metal corresponding to,

residue of a sulpho-monocarboxylic acid, and v and w are small whole numbers such as 1 or 2.

The polyethylene glycol alkyl ether sulphomonocarboxylic acid ester addition agents, whose use represents a particularly preferred embodiment of my present invention, may be represented by the formula where R, M and Y are the same as in the immediately preceding formula, and n is a whole number such as l, 2, 3, 4 or more, preferably 2 to 4. i,

Illustrative examples of addition agents which may be utilized in accordance with my invention and in the concentrations which are, in general, preferred, are shown in Table I Table I Cone, Anion Cation grams/liter 1 circles 2)i-o-crn-oHi-o-oc-orn-sor H tNa or metal or o.1-o.5 v De cyl ether of ethylene glycol sulphoacetate) ba bemg used- 7 (2), OKs-(CH2)11OCH2C 2OOC H2-S0a -ldo--. 0. -0.5

(Lauryl ether of ethylene glycol sulphoacetate) (a) CHg-(Cllz)n-OCH2CHCHzOOCCHz-SOs- Q. 1. o. 5

H (Lauryl mono-ether of glycerol mono-sulphoacctatc) (4 ori a o-C. -G.1 .-O OC-GH.SO.- do '6. 1 -0.6

' (Oetyl ether of diethylene glycol sulphoacetate) AT H 1 l (5 Clix-{CH2}1s 0 C2 4-(OC2 4)20-0 2- 32- "ill- 0- (l tl y ristyl ether of tetraethylene glycol sulphoacetate) (G) CHa(CH2)nO-CH2CHz-O-OC-CHrCHz-SO3T. d.O O. 1.0. 5

(Decyl ether of ethylene glycol sulphopropionat-e) 7 Clix-(CH2)n-(O-CHh-CH-CIfi-hO-OC-CH2-SO3 a o o. 1-q.'s

H (Lauryl mono-ether of diglycerol mono-sulphoacetate) The, water-soluble aliphatic polyhydric alcospecific ethers of which, in the form of monoca'rboxylic acid esters, comprise the onagents of my present invention, may be add in 1H V selebted from a large class and include, for examp glycerin; 'glycols such as ethylene glycol, propyrepg glycol, trimethylene glycol, butylene glycol, and thelike; polyglycols such as diethylene glycol, triethylene glycol, tetraethylene glycol,

the like; pentaerythritol; dipentaerythritol;

polyglycerols such as diglycerol, triglycerol, tetraglyce" li and miizt ur es thereof; carbohydrates and sugars such as dextrose, sucrose, and maltose; and" sugar alcohols such as arabitol, mannitol, sorbitolfdulci'tol, mannitan and sorbitan, and the'like.

"The aliphatic alcohols with which the aforementioned or similar water-soluble aliphatic polyhyd'ric alcohols are etherified may also be selected from a large group including, by way of illustration, straight chain and branched chain alcohols such as octyl alcohol, nonyl alcohol, de'cyl alcohol, undecyl alcohol, lauryl alcohol, myristylalcohol, cetyl alcohol, oleyl alcohol, linoleyl alcohol, stearyl alcohol, ricinoleyl alcohol, and palmitoleyl alcohol, and the like; branched chain octyl, decyl, dodecyl, tetradecyl, hexadecyl and octadecyl aliphatic alcohols as, for example, 2-ethyl heXanol-l; 2-n butyl octanol-l; 2-butyl tetra-decanol-l; 7-ethyl Z-methylundecanol-l; 3,9, diethyltridecanol-G; 3-methylheptanol-2; 5,11 diethylpentadecanol-8; 5-ethylnonanol-2; 7 -ethyl-2 methyltridecanoll; 9-ethyl-5.-methylates, sulphobutyrates, 'sulphovalerates, sulpho-. acrylate's, and the like may also be utilized.

It will be 'iinderstood that the. sulpho-monocarboiiylic'a'cid ra ica is linked to the remainder of the 'rnolecule. of the, addition agent through an hydroxy group of the aliphatic polyhydric alcohol. radical. As indicated. above, the molecule. o f the addition agent may. contain'one or more aliphatic or fatty alcohol radicals and one, or more sulphomonocarbo'xylic acid groups. Of especial utility are the sul-phoacetatesof glycerin, and. glycol paritialethers 'f decyl and lauryl alcohols or'coconut oil miiied'fatty alcohols or special fractions particularly high 'in content of 'deeyl. or, lauryl alcohols.

he addition agents are utilized. preferably in the form, of their freejacids or their alkali metal saltsor in the form 'of 'asalt of the metal to bev electrodepo'sited, In most cases, 'it is preferable More addition agent may be utilized but it is, in

general, uneconomic to do so and fully satisfactory results, are obtained practically all cases with theypreferredrange setout hereinabove.

It will be understood that the addition agents utilized should be soluble in the electrolyte solution 'at least to such an extent as to fall within the general range as set out hereinabove, In,

general, the solubility of the addition agents in the electrolytesolutions decreases with the increase of carbon atoms in the alkyl chain of the addition agents and,'therefore,'lower concentrations of such addition agents may be used. Conversely, higher concentrations, generally speaking, of those addition agents should be used where the number of carbon atoms in the alkyl chain is around 8 or'10 carbon atoms.

w Table II sets forth various examples of plating baths with which the addition agents of the present' invention may be used effectively to prevent or inhibit pitting. It will be understood that these examples are merely illustrative and are not to be taken as 'limitative of my invention, it being understood that, in general, the novel teachings of my invention may be utilized in connection with plating baths wherein the addition agents are soluble in the electrolyte solutions to the extent necessary to accomplish the desired results, and wherein said addition agents are not hydrolyzed or otherwise decomposed or modified to an extent sufficient to interfere with their functioning. In general, the addition agents are particularly effective in aqueous acidic electroplating baths wherein the pH of the bath is of the order of about 2 to about 6.

While, in the examples listed hereinabove in TableII, I have disclosed the use of the sodium I salt of the mono-lauryl ether of diethylene gly- I It will be understood that, from time to time, more addition agent should be added to replenish that which is lost by drag-out or which may possibly be changed, in some manner or other, during the electrodeposition process.

This'application is'a continuation-in-part of my prior application, Serial No. 381,547, filed March, 3, 1941.

What I claim as new and desire to protect by Letters Patent of the United States is:

1. In a process of electrodepositing nickel, the step which comprises electrolyzing an aqueous acid nickel solution of a material selected from the group consisting of nickel sulphate, nickel chloride, and mixtures thereof, said aqueous solution also having dissolved therein a minor proportion of atleast .05 gram per liter of a soluble aliphatic sulpho-monocarboxylic acid ester of a water-soluble aliphatic polyhydric alcohol the Table II [In each oath 0.1-0.5 gram/liter or 0.01-0.07 oz./gal. of mgilitoiauryl other of diethylene glycol sulphoacetate, sodium 5 Nickel (white) 29%, Nickel (white) ffg Ni O4.6-7H2O -40 N1Cl2.6H 0 NiO12.6H2O 8 a 0 H3 0 5 Temp. l00-l50 F--. Temp. -150 F pH=4.0-5.5 H=4.05.5 Cathode C. D., 5-75 amp./ft. Cathode C. D., 5-150 amp./ft.

- cone. cone. Nickel (Bright) ozJgai' Cobalt oL/gaj.

NiSO .67HzO 30-40 CoSOflHzO-.- 30-40 NiClzfiHzO COC12.6HzO- 8 H330: HsBOa 5 CaHy-SOzNHz- (N H4) 23 04 0. 2 ZnSO4.7H2O Temp. -150 Temp. 70120 F pH=3.5-5.5- pH=3.5-5.5 Cathode C D Cathode O. D., 20-200 amp./ft.

Nickel-Cobalt (Bright) ff m Zinc jg NiSO e711 0 s2 znsolmio"; 30-40 cosolvnzo n s znwinsom 4 NlCl2.6H2O 6 A12(SO4)3 2 5 0 198" 0 1? Temp. {ob- F Temp. 100-150 F.. pH=4.0-5.5.. pH=4.0-5.5 Cathode C. D., 5-100 amp./ft. Cathode C. D., 10-50 amp/ft.

cone, conc., hon oz./gal. Copper ozJgal.

(Q id-Ett 2 0 Cl .6H 0... 20 ll 2 a 2, 2--- Tam 106-150" Temp. 70150 F pH=3.55.0. p =3.0-5.0 Cathode C. D., 10-100 amp./ft. Cathode C. D., 10-50 amp/ft!" Iron c0110.,

FeSO4.(NH )2SO4.6H2O 24-32 Temp.Room to F. pH=4-5 Cathode O. D., 5-100 amp/ft.

hydrogen of at least one hydroxy group of which is replaced by an alkyl radical containing from -lgal. 70 8 t 18 carbon atoms, the sulpho-monocarboxylic 7 acid nickel solution of a material selected from the group consisting of nickel sulphate, nickel chloride, and mixtures thereof, said aqueous solution also having dissolved therein a minor proportion of at least .05 gram per liter of the lauryl mono-ether of diethylene glycol sulphoacetate.

3. A bath for the electrodeposition of nickel consisting essentially of an aqueous acid solution of a material selected from the group con sishting of nickel sulphate, nickel chloride, and mixtures thereof, and a minor proportion of at least .05 gram per liter of a soluble aliphatic sulpho-fatty acid ester of a water-soluble aliphatic polyhydric alcohol the hydrogen of at least one hydroxy group of which is replaced by an alkyl radical containing from 8 to 18 carbon atoms, the sulpho-fatty acid radical containing from 2 to 6 carbon atoms inclusive.

4. A bath for the electrodeposition of nickel 8 consisting essentially of an aqueous acid solution of a material selected from the group consisting of nickel sulphate, nickel chloride, and mixtures thereof, and a minor proportion of at least .05 gram per liter of a mono-sulphoacetate of a lauryl mono-ether of a glycol.

HENRY BROWN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,389,135 Brown Nov. 20, 1945 2,389,179 Brown Nov. 20, 1945 2,389,180 Brown Nov. 20, 1945 2,389,181 Brown Nov. 20, 1945 

1. IN PROCESS OF ELECTRODEPOSITION NICKEL, THE STEP WHICH COMPRISES ELECTROLYZING AN AQUEOUS ACID NICKEL SOLUTION OF SULPHATE NICKEL CHLORIDE, AND MIXTURE THEREOF, SAID AQUEOUS SOLUTION ALSO HAVING DISSOLVED THEREIN A MINOR PROPORTION OF AT LEAST .05 GRAM PER LITER OF A SOLUBLE ALIPHATIC SULPHO-MONOCARBOXYLIC ACID ESTER OF A WATER-SOLUBLE ALIPHATIC POLYHYDRIC ALCOHOL THE HYROGEN OF AT LEAST ONE HYDROXY GROUP OF WHICH IS REPLACED BY AN ALKYL RADICAL CONTAINING FROM 8 TO 18 CARBON ATOMS, THE SULPHO-MONOCARBOXYLIC ACID RADICAL CONTAINING FROM 2 TO 6 CARBON ATOMS INCLUSIVE. 